Field of the Invention
The invention relates to a combined jet engine provided with means for switching between two operating states such as a turbojet operation and a ram jet operation.
Turbojet operation is preferred up to an aircraft speed roughly four times the speed of sound (Mach 4), but it is necessary to pass into the ram jet mode for obtaining even higher speeds (up to Mach 7 or 8). As the air then reaches a very high temperature, it must be made to skirt the gas turbine mainly forming the turbojet and it is for this purpose that the jet engine stream is subdivided over part of its length between a central turbojet stream where the turbine is located and a peripheral stream surrounding the latter and where the ram jet burners are located. However, it is necessary to provide means for obstructing one or the other of the two streams in order to guide all the air into the stream associated with the chosen operation mode.